Prothena (PRTA) 10% Owner Scully William P Buys $843K of Stock

William Scully, a 10% owner of Prothena Corporation plc (PRTA on NasdaqGS), bought 100,000 shares on September 18, 2026, for about $843,460. This purchase comes as part of Scully's ongoing commitment to the biotech firm, which focuses on developing therapies for diseases caused by protein dysregulation.

Inside Scully's Trade

Scully's recent purchase adds significantly to his stake in Prothena. This buy was executed at a price of $8.43 per share. This trade is part of a series of recent transactions where Scully has shown strong interest in increasing his ownership in the company.

Other Institutional Activity in Prothena

FMR, LLC reduced its holdings by 351,881 shares, ending with 7,199,218 shares valued at about $60.7 million. Blackrock Inc. grew its position by 223,846 shares, bringing its total to 4,867,955 shares worth approximately $41.1 million. State Street Corporation added 454,958 shares, increasing its total to 2,393,424 shares valued at about $20.2 million, while Acadian Asset Management increased its stake by 463,043 shares, ending with 2,010,645 shares worth around $16.96 million.

Prothena Corporation plc Stock Down 0.1%

Prothena's stock closed at $8.58 before Scully's latest purchase. The stock has traded between $7.73 and $11.80 over the past year. This recent activity comes as the company prepares for its next earnings report on November 5, 2026.

Recent Earnings

In its most recent quarter, Prothena reported revenue of $54.53 million, reflecting a decline from prior periods. The company is currently not profitable, with an EPS of -0.82. The upcoming earnings date could provide further insights into its financial health.

Insider Buying and Selling at Prothena Corporation plc

In addition to his recent purchase, Scully also bought 10,000 shares on October 14, 2026, for about $84,569, and previously acquired 100,000 shares on October 13, 2026, at a price of $8.35, totaling approximately $835,480. Earlier in June, he purchased 20,000 shares at $7.90 each for about $158,000. These transactions show Scully's continued investment in Prothena.

About Prothena

Prothena Corporation plc is a biotechnology company based in Dublin, Ireland. It specializes in discovering and developing therapies for diseases linked to protein dysregulation. Its leading product, Prasinezumab, is in Phase 3 clinical trials for treating Parkinson's disease and other related conditions.

Bottom Line

Investors should keep an eye on Prothena's upcoming earnings report on November 5, 2026, which could provide more insight into the company's performance. As a reminder, insider transactions reflect past actions and may not indicate current positions.